Pharmacology · Antimuscarinics (anticholinergics)
Hyoscine butylbromide !
A gut antispasmodic widely used in Colombia for cramping abdominal pain. It is a quaternary drug that does not enter the brain.
Updated 2026-11-01
Also called: Butylscopolamine, Scopolamine butylbromide
No structure of hyoscine butylbromide bound to its receptor exists. The figure shows N-methylscopolamine, the quaternary form of scopolamine and a close relative, in the acetylcholine (orthosteric) pocket of the human M2 muscarinic receptor; all muscarinic subtypes share this pocket.
Mechanism of action
Adding a butyl group to scopolamine makes a charged quaternary molecule. It blocks muscarinic receptors on the smooth muscle of the gut, so spasm and cramping ease; it acts on the cause of the pain (the spasm) rather than masking pain like an analgesic. Because it is charged it is poorly and unreliably absorbed by mouth and does not cross the blood-brain barrier, so it causes no drowsiness or confusion; quaternary derivatives also have some ganglion-blocking activity.
- Blocks muscarinic receptors on gut smooth muscle
- Acetylcholine can no longer trigger contraction
- Spasm and cramping pain ease
- Stays out of the brain (quaternary)
Pharmacokinetics
- Absorption
- Poorly and unreliably absorbed by mouth; injections act more reliably
- Distribution
- Does not cross the blood-brain barrier
Indications
- Cramping abdominal pain from spasm of the gut
- Symptom control in palliative care (WHO Essential Medicines List)
Adverse effects
Common
- Dry mouth
- Fast heart rate
- Blurred vision
- Urinary hesitancy, constipation
Contraindications
- Angle-closure glaucoma
- Urinary retention or bladder outlet obstruction (for example an enlarged prostate)
- Mechanical obstruction of the gut, paralytic ileus or toxic megacolon
- Myasthenia gravis
- Unstable heart status with fast heart rate (class precaution)
Key interactions
- Other anticholinergic drugs (tricyclics, antihistamines, antipsychotics)
- Additive dry mouth, retention and constipation
- Metoclopramide
- Opposite effects on gut motility (class)
What is monitored
- Heart rate, especially after injection
- Urine output and bladder in older men
- Pain that persists or worsens is reassessed for another cause
Administration and safety
- Tablets or injection; injection gives the more reliable effect
- In Colombia it is sold both with and without prescription; it should not be confused with scopolamine (hyoscine hydrobromide)
Nursing care
- Ask about glaucoma, prostate problems and heart disease before giving it
- Check pulse after injection
- Teach to report eye pain with red eye and blurred vision, or inability to pass urine
Pregnancy and breastfeeding
Data in pregnancy are limited; it is used only when the benefit justifies it.
Test yourself
Think of the answer, then tap the question to see it.
Why does hyoscine butylbromide not cause drowsiness or confusion, unlike scopolamine?
It is a quaternary (charged) molecule that does not cross the blood-brain barrier.
Why does oral hyoscine butylbromide act less reliably than the injection?
Quaternary antimuscarinics are poorly and unreliably absorbed from the gut.
Which eye disease must be asked about before giving it?
Angle-closure glaucoma.
Related drugs
← Back to the class: Antimuscarinics (anticholinergics)
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Comportamiento de las intoxicaciones con escopolamina durante 2021-2022 (Secretaría Distrital de Salud de Bogotá (Boletín Epidemiológico Distrital), 2022); eEML - Electronic Essential Medicines List (World Health Organization, 2025); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 11 (McGraw Hill, 2023).
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Representative model, for educational purposes only.